The links between the gut microbiome and non-alcoholic fatty liver disease (NAFLD)

Gut microbiota dysbiosis contributes to choline unavailability and NAFLD development

Objectives

Non-alcoholic fatty Liver Disease (NAFLD) poses a growing global health concern, yet its complex aetiology remains incompletely understood. Emerging evidence implicates the gut microbiome and choline metabolism in NAFLD pathogenesis. This study aims to elucidate the association of choline-consuming bacteria in gut microbiome with choline level.

Methods

A population comprising 85 NAFLD patients and 30 healthy controls was selected. DNA extraction from stool samples was conducted using the FavorPrep™ Stool DNA Isolation Mini Kit, followed by polymerase chain reaction (PCR) detection of choline-consuming bacterial strains and quantitative PCR (qPCR) for Cut C gene expression. Choline content measurement was performed using fluorescence high-performance liquid chromatography (FL-HPLC).

Results

Our findings revealed a significant reduction in choline levels among NAFLD patients compared to healthy controls. ROC curve analysis demonstrated choline levels and Cut C expression as a promising diagnostic tool for NAFLD, with high sensitivity and specificity. The microbial analysis identified specific choline-consuming bacteria enriched in NAFLD patients, notably Anarococcus Hydrogenalis and Clostridium asparagiforme. This was consistent with higher Cut C gene expression in patients compared to healthy individuals, which is responsible for encoding an enzyme to consume choline by these bacteria.

Conclusion

The current study gives a possible association between gut microbiota and the development of NAFLD, possibly due to an alteration in choline bioavailability. Further research is required to determine whether gut bacteria alter in the context of NAFLD or a change in their composition might lead to NAFLD progression, possibly via alternation in choline bioavailability.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40200-024-01511-6.

HIIT versus MICT in MASLD: mechanisms mediated by gut-liver axis crosstalk, mitochondrial dynamics remodeling, and adipokine signaling attenuation

OBJECTIVE

Compare the effects of high-intensity interval training (HIIT) and moderate-intensity continuous training (MICT) on metabolic dysfunction-associated steatotic liver disease (MASLD), focusing on the mechanisms by which these two exercise modalities influence gut microbiota structure, bile acid metabolism, and intestinal barrier function, as well as their regulatory roles in hepatic lipid synthesis and oxidative dynamics. Explore the synergistic effects of exercise-mediated mitochondrial fusion remodeling and leptin signaling, elucidate the causal relationship between gut-derived factors and hepatic metabolic reprogramming, and reveal the potential multi-scale and cross-organ dominant mechanisms of exercise, providing a theoretical basis for systematically comparing the effects of different exercise modalities.

METHODS

Thirty-two male rats were randomly divided into NFD (n = 8) and HFD (n = 24) groups and fed normal chow and high-fat chow, respectively. After eight weeks, the HFD group was randomly divided into three groups: (1) MICT-8; (2) HIIT-8; and (3) HFD-8. At the end of the experiment, blood, liver, ileum, and skeletal muscle samples were collected for analysis of the rats' baseline conditions, mitochondrial function, hepatic lipid metabolism, bile acid pathway and gut microbiota, and synthesis of analyses.

RESULTS

Both modes of exercise ameliorated metabolic dysregulation and attenuated pathological progression, insulin resistance, and liver fat accumulation in rats with MASLD. Furthermore, both interventions counteracted HFD-induced intestinal barrier dysfunction and restored gut-liver axis homeostasis. HIIT and MICT also upregulated bile acid-related gene expression modulated butyrate-producing bacterial taxa, and adjusted the abundance of butyrate-generating bacteria.

CONCLUSION

Both HIIT and MICT improved lipid metabolism in MASLD rats and the difference between the HIIT and MICT groups was not statistically significant. It is noteworthy that HIIT was more effective in improving mitochondrial function in MASLD than MICT (P < 0.001).

Bifidobacterium adolescentis prevents diabetes-induced liver injury via pyroptosis attenuation

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD), along with non-alcoholic steatohepatitis (NASH), lacks definitive therapy and typically remains asymptomatic until reaching advanced stages. Lipid metabolism and inflammation management using probiotics such as Bifidobacterium adolescentis is suggested to alleviate or suppress NAFLD development. Hence, this study aims to investigate the effects of Bifidobacterium adolescentis treatment on mitigating pyroptosis, an inflammatory cell death pathway, in the liver of rats with NAFLD induced by high-fat diet (HFD) and streptozotocin (STZ) administration.

METHODS

Forty 8-week adult male Sprague Dawley rats were divided into four groups. Bifidobacterium adolescentis was administered for 8 and 16 weeks at 4 × 1010 CFU/day to rats fed a high-fat diet (HFD). Subsequently, the mRNA expression levels of pyroptotic-related genes including Cas1, Cas3, Cas11, NLRP3, GSDMD, IL-1β, and NF-κB were quantified in liver tissue using quantitative polymerase chain reaction (qPCR). Histopathological alterations and stereological changes in liver structure, as well as lipid profile (FBG, TG, TC, HDL, LDL), and liver indices (ALT, AST, ALP, LDH), were also evaluated across the different groups.

RESULTS

Bifidobacterium adolescentis administration significantly reduced the expression levels of NF-κB and pyroptotic-related genes. Additionally, this probiotic effectively reversed the adverse effects of the high-fat diet (HFD) on liver volume, Kupffer cell numbers, and hepatocyte nuclei. Furthermore, it improved the lipid profile and liver indices of rats fed with the HFD.

CONCLUSION

This study demonstrates that B. adolescentis supplementation prevents diabetes-induced liver injury by attenuating pyroptosis. These findings suggest that Bifidobacterium adolescentis may be a promising therapeutic approach for managing NAFLD and its associated complications, primarily by modulating key genes associated with pyroptosis and inflammation in rats fed with a high-fat diet.

IL-5-producing Group 2 innate lymphoid cells promote T cell-independent IgA production in cooperation with eosinophils

Intestinal bacteria play a critical role in the regulation of the host immune system and an imbalance in the intestinal bacterial composition induces various host diseases. Therefore, maintaining a balance in the intestinal bacterial composition is crucial for health. Immunoglobulin A (IgA), produced through T cell-dependent and T cell-independent (TI) pathways, is essential for host defense against pathogen invasion and maintaining the balance of intestinal symbiotic bacteria. Interleukin (IL)-5 is constitutively produced by Group 2 innate lymphoid cells (ILC2s) and plays a critical role in the survival and proliferation of B cells and eosinophils. Here, we show the role of IL-5-producing ILC2s in intestinal TI IgA production at steady state using T cell receptor α deficient mice. In this mouse model, ILC2s increased fecal TI IgA levels in a non-inflammatory state in an IL-5-dependent manner. The administration of recombinant IL-33 (rIL-33) increased the amount of TI IgA production, accompanied by an increase in the number of IL-5-producing ILC2s in the large intestine. In addition, rIL-33 treatment increased IL-5-dependent IgA+ cells in isolated lymphoid follicles, the site of TI IgA production. Furthermore, eosinophils recruited by ILC2s were required for the maximal production of IgA in the TI pathway. Moreover, IL-5 increased the frequency of TI IgA-binding intestinal bacteria and was involved in the maintenance of intestinal bacterial composition. These findings indicate that IL-5-producing ILC2s together with eosinophils contribute to TI IgA production. In addition to their role in TI IgA production, IL-5-producing ILC2s may contribute to the homeostasis of intestinal commensal bacteria.

Polyethylene terephthalate microplastics affect gut microbiota distribution and intestinal damage in mice

Polyethylene terephthalate microplastics (PET-MPs) have been detected in the environment and human metabolites or tissues; however, their potential effects on humans under actual exposure doses remain unclear. Herein, male adult mice were exposed to 10 µm PET-MPs at concentrations of 10, 50, and 250 mg/kg per body weight consecutively for 28 days. Changes in blood biochemistry, inflammatory factors, colonic histopathology, colonic mucus gene mRNA levels, and the gut microflora were monitored to study PET-MPs toxicity. The results showed that PET-MPs exposure increased relative serum alanine aminotransferase (ALT) and glucose (GLU) levels in 50 mg/kg bw PET-MPs exposure group, and altered relative levels of inflammatory factors, thereby inducing the inflammatory response. Moreover, PET-MPs exposure increased mRNA expression levels of colonic mucus secretion related and barrier function related genes, indicating intestinal mucus secretion and barrier integrity dysfunction, which was consistent with the results of histopathological results. In addition, gut microbiota analysis revealed that the diversity and community composition were altered after PET-MPs exposure, suggesting a metabolic disorder. Therefore, our results demonstrated that exposure to PET-MPs led to intestinal injury and changes in the gut microbiome composition in mice. Overall, the study findings provided basic data about the health risks of PET-MPs to humans, highlighting that MPs-induced toxicity warrants more concern in the future.

Gut microbiota differences, metabolite changes, and disease intervention during metabolic - dysfunction - related fatty liver progression

In the current era, metabolic dysfunction-associated steatotic liver disease (MASLD) has gradually developed into a major type of chronic liver disease that is widespread globally. Numerous studies have shown that the gut microbiota plays a crucial and indispensable role in the progression of MASLD. Currently, the gut microbiota has become one of the important entry points for the research of this disease. Therefore, the aim of this review is to elaborate on the further associations between the gut microbiota and MASLD, including the changes and differences in the microbiota between the healthy liver and the diseased liver. Meanwhile, considering that metabolic dysfunction-associated fatty liver and metabolic dysfunction-associated steatohepatitis are abnormal pathological states in the development of the disease and that the liver exhibits different degrees of fibrosis (such as mild fibrosis and severe fibrosis) during the disease progression, we also conduct a comparison of the microbiota in these states and use them as markers of disease progression. It reveals the changes in the production and action mechanisms of short-chain fatty acids and bile acids brought about by changes in the gut microbiota, and the impact of lipopolysaccharide from Gram-negative bacteria on the disease. In addition, the regulation of the gut microbiota in disease and the production and inhibition of related disease factors by the use of probiotics (including new-generation probiotics) will be explored, which will help to monitor the disease progression of patients with different gut microbiota compositions in the future and carry out personalized targeted therapies for the gut microbiota. This will achieve important progress in preventing and combating this disease.

N6-Methyladenosine Modification in the Metabolic Dysfunction-Associated Steatotic Liver Disease

Epigenetics of N6-methyladenine (m6A) modification may play a key role during the regulation of various diseases, including metabolic dysfunction-associated steatotic liver disease (MASLD). The m6A modification has been shown to be accomplished via the exploitation of several players such as methyltransferases, demethylases, and/or methylation-binding molecules. Significantly, the m6A methylation can regulate the key eukaryotic transcriptome by affecting the subcellular localization, splicing, export, stability, translation, and decay of those RNAs. An increasing amount of data has designated that the m6A modification of RNAs can also modulate the expression of autophagy-related genes, which could also control the autophagy in hepatocytes. Oxidative stress with reactive oxygen species (ROS) can induce m6A RNA methylation, which might be associated with the regulation of mitochondrial autophagy (mitophagy) and/or the development of MASLD. Therefore, both autophagy and the m6A modification could play important roles in regulating the pathogenesis of MASLD. Comprehending the relationship between m6A and mitophagy may be helpful for the development of future therapeutic strategies against MASLD. This review would advance the understanding of the regulatory mechanisms of m6A RNA modification, focusing on the impact of mitochondrial dysregulation and mitophagy in the liver with MASLD.

Gut microbiota in the development and progression of chronic liver diseases: Gut microbiota-liver axis

The gut microbiota (GM) is a highly dynamic ecology whose density and composition can be influenced by a wide range of internal and external factors. Thus, "How do GM, which can have commensal, pathological, and mutualistic relationships with us, affect human health?" has become the most popular research issue in recent years. Numerous studies have demonstrated that the trillions of microorganisms that inhabit the human body can alter host physiology in a variety of systems, such as metabolism, immunology, cardiovascular health, and neurons. The GM may have a role in the development of a number of clinical disorders by producing bioactive peptides, including neurotransmitters, short-chain fatty acids, branched-chain amino acids, intestinal hormones, and secondary bile acid conversion. These bioactive peptides enter the portal circulatory system through the gut-liver axis and play a role in the development of chronic liver diseases, cirrhosis, and hepatic encephalopathy. This procedure is still unclear and quite complex. In this study, we aim to discuss the contribution of GM to the development of liver diseases, its effects on the progression of existing chronic liver disease, and to address the basic mechanisms of the intestinal microbiota-liver axis in the light of recent publications that may inspire the future.

The interaction between various food components and intestinal microbiota improves human health through the gut-X axis: independently or synergistically

Food contains various components that improve health by affecting the gut microbiota, primarily by modulating its abundance or altering its diversity. Active substances in food have different effects on the gut microbiota when they act alone or in synergy, resulting in varying impacts on health. The bioactive compounds in food exert different effects on various gut microbiota through multiple pathways, thereby delaying or preventing different kinds of disease. The combination of two or more active compounds may have a synergistic effect, which can more effectively alter the gut microbiota and alleviate diseases through the microbiota-gut-organ axis. According to reports, multiple different food components have similar effects, some of which have been shown to have a synergistic effect on the gut microbiota to promote health. However, there is currently no systematic review of its synergistic effects and mechanisms. There may be more compounds with synergistic effects that have not yet been discovered, while their mechanisms of synergy and ways of impacting host health through the gut microbiota deserve further investigation. The purpose of this review is to systematically summarize the effects of different food components on intestinal flora and health, and further analyze the potential synergies between different food components. PubMed and Google Scholar databases were searched in this review.

Effect of Probiotics on Improving Intestinal Mucosal Permeability and Inflammation after Surgery

Background/Aims

We explored the mechanisms underlying the improvement of postoperative ileus (POI) following probiotic pretreatment. We assessed intestinal permeability, inflammation, tight junction (TJ) protein expression in the gut epithelium, and plasma interleukin (IL)-17 levels in a guinea pig model of POI.

Methods

Guinea pigs were divided into control, POI, and probiotic groups. The POI and probiotic groups underwent surgery, but the probiotic group received probiotics before the procedure. The ileum and proximal colon were harvested. Intestinal permeability was measured via horseradish peroxidase permeability. Inflammation was evaluated via leukocyte count in the intestinal wall muscle layer, and calprotectin expression in each intestinal wall layer was analyzed immunohistochemically. TJ proteins were analyzed using immunohistochemical staining, and plasma IL-17 levels were measured using an enzyme-linked immunosorbent assay.

Results

The POI group exhibited increased intestinal permeability and inflammation, whereas probiotic pretreatment reduced the extent of these POI-induced changes. Probiotics restored the expression of TJ proteins occludin and zonula occludens-1 in the proximal colon, which were increased in the POI group. Calprotectin expression significantly increased in the muscle layer of the POI group and was downregulated in the probiotic group; however, no distinct differences were observed between the mucosal and submucosal layers. Plasma IL-17 levels did not significantly differ among the groups.

Conclusions

Probiotic pretreatment may relieve POI by reducing intestinal permeability and inflammation and TJ protein expression in the gut epithelium. These findings suggest a potential therapeutic approach for POI management.

The association between the dietary index for gut microbiota and non-alcoholic fatty liver disease and liver fibrosis: evidence from NHANES 2017-2020

BACKGROUND

Imbalance in the gut microbiota is a key factor in the pathogenesis of non-alcoholic fatty liver disease (NAFLD) and liver fibrosis. The Dietary Index for Gut Microbiota (DI-GM) integrates the potential relationship between diet and gut microbiota diversity. This study aims to investigate the association between DI-GM and the risk of NAFLD and liver fibrosis, providing theoretical support for dietary intervention strategies.

METHODS

This study utilized data from NHANES 2017-2020, including 6,181 eligible adult participants. The relationship between DI-GM and the risk of NAFLD and liver fibrosis was assessed using DI-GM quartiles, multivariate logistic regression, and restricted cubic spline (RCS) analysis. Subgroup analysis was performed to explore the predictive role of DI-GM in different populations. All analyses were weighted to ensure the representativeness of the results.

RESULTS

DI-GM was negatively associated with the risks of NAFLD and liver fibrosis. As DI-GM scores increased, the risk of NAFLD and liver fibrosis significantly decreased (52.81%, 43.16%, 40.40%, and 31.98%, p < 0.05; 17.52%, 9.04%, 7.21%, and 6.78%, p < 0.05). Multivariate logistic regression analysis revealed that, in the unadjusted model (Model 1), for each unit increase in DI-GM, the risk of NAFLD decreased by 6.9% (OR = 0.931, 95% CI: 0.886-0.979, p < 0.001), while the risk of liver fibrosis decreased by 15.6% (OR = 0.844, 95% CI: 0.757-0.941, p < 0.05). In the quartile analysis, individuals in the highest DI-GM quartile (Q4) had a 58% lower risk of NAFLD compared to those in the lowest quartile (Q1) (OR = 0.42, 95% CI: 0.219-0.806, p < 0.001). The results remained significant even after adjusting for covariates. RCS analysis showed that DI-GM had a nonlinear relationship with the risks of NAFLD and liver fibrosis, with inflection points at scores of 2 and 5, indicating enhanced protective effects.

CONCLUSION

This study reveals a negative association between DI-GM and the risk of NAFLD and liver fibrosis, highlighting the potential role of healthy dietary patterns in the prevention and management of NAFLD and liver fibrosis through gut microbiota modulation, providing a theoretical basis for dietary interventions.

Novel translational mouse models of metabolic dysfunction-associated steatotic liver disease comparable to human MASLD with severe obesity

OBJECTIVE

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common cause of chronic liver disease, especially in patients with severe obesity. However, current mouse models for MASLD do not reflect the polygenetic background nor the metabolic changes in this population. Therefore, we investigated two novel mouse models of MASLD with a polygenetic background for the metabolic syndrome.

METHODS

TALLYHO/JngJ mice and NONcNZO10/LtJ mice were fed a high-fat- high-carbohydrate (HF-HC) diet with a surplus of cholesterol diet. A second group of TH mice was additional treated with empagliflozin.

RESULTS

After sixteen weeks of feeding, both strains developed metabolic syndrome with severe obesity and histological manifestation of steatohepatitis, which was associated with significantly increased intrahepatic CD8+cells, CD4+cells and Tregs, contributing to a significant increase in pro-inflammatory and pro-fibrotic gene activation as well as ER stress and oxidative stress. In comparison with the human transcriptomic signature, we could demonstrate a good metabolic similarity, especially for the TH mouse model. Furthermore, TH mice also developed signs of kidney injury as an extrahepatic comorbidity of MASLD. Additional treatment with empagliflozin in TH mice attenuates hepatic steatosis and improves histological manifestation of MASH.

CONCLUSIONS

Overall, we have developed two promising new mouse models that are suitable for preclinical studies of MASLD as they recapitulate most of the key features of MASLD.

Improving fatty liver hemorrhagic syndrome in laying hens through gut microbiota and oxylipin metabolism by Bacteroides fragilis: A potential involvement of arachidonic acid

Bacteroides fragilis (B. fragilis), a crucial commensal bacterium within the gut, has shown connections with hepatic lipid metabolism and inflammation regulation. Nonetheless, the role of B. fragilis in the progression of fatty liver hemorrhagic syndrome (FLHS) remains unknown. This study aims to explore the ameliorative effects of B. fragilis on FLHS in laying hens, as well as its underlying mechanisms. This is the first study to employ a chicken FLHS model, combining microbiomics and oxylipin metabolomics to investigate the mechanism of action of intestinal symbiotic bacteria. Exp. 1: 40 laying hens at 25 weeks old were randomly divided into five treatment groups (eight replicates per group and one hen per replicate), including the control group (basal diet), the high-energy and low-protein (HELP) group, and the HELP group with three different levels (108, 109, and 1010 CFU) of B. fragilis. Exp. 2: 18 chickens at 25 weeks old were randomly divided into three treatment groups (six replicates per group and one hen per replicate) including the control group (basal diet), the model group (HELP diet), and the arachidonic acid (AA) group (HELP diet with 0.3% AA). The experiment period of Exp. 1 and Exp. 2 were 8 weeks. B. fragilis significantly improved body weight of seventh week (P = 0.006), liver lipid degeneration, blood lipid levels (triglycerides, cholesterol, and low-density lipoprotein cholesterol; P < 0.05), and liver function (alanine aminotransferase and aminotransferase; P < 0.05) in laying hens. B. fragilis downregulated the expression of lipid synthesis-related genes fatty acid synthase, acetyl-CoA carboxylase, and liver X receptor α, and inflammation-related genes tumor necrosis factor α, interleukin (IL)-1β, IL-6, and IL-8 in the liver of FLHS-affected hens (P < 0.05), while upregulating the expression of lipid oxidation-related genes carnitine palmitoyl transferase-1, peroxisome proliferator activated receptor (PPAR) α, and PPARγ (P < 0.05). The in-depth analysis indicated alterations in oxylipin pathways triggered by B. fragilis, as evidenced by changes in the expression of pivotal genes arachidonate 15-lipoxygenase, arachidonate 5-lipoxygenase (P < 0.05), subsequently causing modifications in relevant metabolites. This included a decrease in pro-inflammatory substances such as 15-oxoETE (P = 0.004), accompanied by an increase in AA (P = 0.008). B. fragilis regulated the homeostasis of intestinal flora by increasing the abundance of Bacteroides and decreasing the abundance of Succinatimonas and Faecalicoccus (P < 0.05). The integrated analysis revealed a robust positive correlation between Bacteroides abundance and AA levels (P = 0.007). This relationship was corroborated through in vitro experiments. Subsequently, the beneficial effect of AA in mitigating FLHS was confirmed in laying hens with FLHS, further supported by reverse transcription-polymerase chain reaction analysis demonstrating gene expression patterns akin to B. fragilis intervention. This study demonstrated that B. fragilis exerts an anti-FLHS effect through modulation of oxylipin metabolism and gut microbiota stability, with a pivotal role played by AA.

Gut microbiota therapy in gastrointestinal diseases

The human gut microbiota, consisting of trillions of microorganisms, plays a crucial role in gastrointestinal (GI) health and disease. Dysbiosis, an imbalance in microbial composition, has been linked to a range of GI disorders, including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), celiac disease, and colorectal cancer. These conditions are influenced by the interactions between the gut microbiota, the host immune system, and the gut-brain axis. Recent research has highlighted the potential for microbiome-based therapeutic strategies, such as probiotics, prebiotics, fecal microbiota transplantation (FMT), and dietary modifications, to restore microbial balance and alleviate disease symptoms. This review examines the role of gut microbiota in the pathogenesis of common gastrointestinal diseases and explores emerging therapeutic approaches aimed at modulating the microbiome. We discuss the scientific foundations of these interventions, their clinical effectiveness, and the challenges in their implementation. The review underscores the therapeutic potential of microbiome-targeted treatments as a novel approach to managing GI disorders, offering personalized and alternative options to conventional therapies. As research in this field continues to evolve, microbiome-based interventions hold promise for improving the treatment and prevention of gastrointestinal diseases.

Protein hydrolysate from Atlantic salmon (Salmo salar) improves aging-associated neuroinflammation and cognitive decline in rats by reshaping the gut microbiota and Th17/Treg balance

As the global population ages, cognitive decline in older adults has gained significant attention in public health, underscoring the urgent need for effective intervention strategies. This study investigates the impact of salmon protein hydrolysate (SPH) on gut microbiota and cognitive decline in aged rats. Over 8 weeks, aged Sprague-Dawley rats were treated with SPH, resulting in significant enhancements in cognitive function as evidenced by operant-based attentional set-shifting and Morris water maze tasks. SPH modulated microglial activation in the hippocampus, reducing M1 polarization and promoting M2 polarization. RT-PCR analysis indicated a decrease in pro-inflammatory cytokines and an increase in anti-inflammatory cytokines, suggesting a reduction in neuroinflammation. Additionally, 16S rRNA gene sequencing revealed that SPH transformed gut microbiota, increasing Bacteroidetes and decreasing Proteobacteria. The bacterial genera Prevotella, Bacteroidetes and Ruminococcus showed notable increases. Furthermore, SPH intervention can also increase the concentrations of certain short-chain fatty acids (SCFAs) in aged rats. Additionally, SPH also restored the Th17/Treg balance and decreased peripheral inflammation. This study offers compelling evidence for SPH as a functional food that may mitigate cognitive decline due to aging.

Association of daily sleep duration with risk of metabolic dysfunction-associated steatotic liver disease and adverse liver outcomes

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is the most common liver disease worldwide, leading to substantial disease burden globally. Whether sleep duration is associated with the risk of MASLD, cirrhosis, hepatocellular carcinoma (HCC), and liver-related mortality remains underexplored.

METHODS

A total of 489,261 middle-aged and older adults from the UK Biobank without prior liver diseases were included. The primary outcome was MASLD, with secondary outcomes, including cirrhosis, HCC, and liver-related mortality ascertained through linked hospital records and death registries. Sleep duration was self-reported at baseline survey and categorized into ≤ 5, 6, 7, 8 and ≥ 9 hours.

RESULTS

During a median (IQR) follow-up of 13.8 (1.5) years, 7,133 MASLD, 5,527 cirrhosis, 1,126 HCC, and 1,125 liver-related mortality cases were identified. After adjusting for potential confounders, the HRs [95% CIs] of MASLD were 1.44 [1.32;1.57], 1.17 [1.09;1.24], 1.00 (reference), 1.05 [0.99;1.11] and 1.35 [1.24;1.46] for ≤ 5, 6, 7, 8 and ≥ 9 hours of sleep duration, respectively. Similar trends were also observed for cirrhosis, HCC, and liver-related mortality. In addition, the U-shaped association between sleep duration and MASLD was more pronounced among participants without abnormal body mass index (overweight and obese), hypertension or insomnia (P for interaction <0.05).

CONCLUSIONS

Both short and long sleep duration are associated with an increased risk of MASLD, cirrhosis, HCC, and liver-related mortality. Maintaining a moderate sleep duration of 7 to 8 hours per day could be crucial to prevent against this escalating public health concern.

Effects of dietary live microbes intake on a newly proposed classification system for steatotic liver disease

Steatotic liver disease (SLD) is a common chronic liver disease without effective therapeutic options. Some studies suggest potential health benefits of dietary live microbes. This study aims to investigate the association between dietary live microbes intake and metabolic dysfunction-associated steatotic liver disease (MASLD) / metabolic alcohol-related liver disease (MetALD) / alcoholic liver disease (ALD) in adults. Data from the National Health and Nutrition Examination Survey 1999-2018 were analyzed. MASLD was defined according to the latest Delphi Consensus standard. Participants were grouped based on estimated dietary live microbe intake: low (< 104 CFU/g), moderate (104-107 CFU/g), and high (> 107 CFU/g). Multivariable logistic regression analysis was employed to assess the impact of dietary live microbes on MASLD/MetALD/ALD, along with further investigations into non-dietary probiotic/prebiotic relationships. Participants had a weighted mean age of 47.05 years (SE, 0.24) and 50.59% were female. MASLD proportions differ among low (21.76%), moderate (22.24%), and high (18.96%) microbe groups. Similarly, for MetALD, proportions are 7.75%, 6.95%, and 6.44%, and for ALD, 5.42%, 3.59%, and 2.97% in respective groups. The high dietary live microbe intake group was associated with a 16% lower risk of MASLD compared to those in the low intake group (trend test, P = 0.02), while the risk of ALD was reduced by 25% in the moderate intake group. A lack of association was identified between non-dietary prebiotic/probiotic and MASLD/MetALD/ALD. Our study suggests that a relatively high intake of live microbes diets in adults is associated with a lower risk of SLD.

Therapeutic Strategies to Modulate Gut Microbial Health: Approaches for Chronic Metabolic Disorder Management

Numerous recent studies have suggested that the composition of the intestinal microbiota can trigger metabolic disorders, such as diabetes, prediabetes, obesity, metabolic syndrome, sarcopenia, dyslipidemia, hyperhomocysteinemia, and non-alcoholic fatty liver disease. Since then, considerable effort has been made to understand the link between the composition of intestinal microbiota and metabolic disorders, as well as the role of probiotics in the modulation of the intestinal microbiota. The aim of this review was to summarize the reviews and individual articles on the state of the art regarding ideal therapy with probiotics and prebiotics in order to obtain the reversion of dysbiosis (alteration in microbiota) to eubiosis during metabolic diseases, such as diabetes, prediabetes, obesity, hyperhomocysteinemia, dyslipidemia, sarcopenia, and non-alcoholic fatty liver diseases. This review includes 245 eligible studies. In conclusion, a condition of dysbiosis, or in general, alteration of the intestinal microbiota, could be implicated in the development of metabolic disorders through different mechanisms, mainly linked to the release of pro-inflammatory factors. Several studies have already demonstrated the potential of using probiotics and prebiotics in the treatment of this condition, detecting significant improvements in the specific symptoms of metabolic diseases. These findings reinforce the hypothesis that a condition of dysbiosis can lead to a generalized inflammatory picture with negative consequences on different organs and systems. Moreover, this review confirms that the beneficial effects of probiotics on metabolic diseases are promising, but more research is needed to determine the optimal probiotic strains, doses, and administration forms for specific metabolic conditions.

Polysaccharides from hawthorn fruit alleviate high-fat diet-induced NAFLD in mice by improving gut microbiota dysbiosis and hepatic metabolic disorder

BACKGROUND

Hawthorn fruit, renowned as both a functional food and herbal medicine with lipid-lowering effects, is abundant in polysaccharides. However, there is limited research on the effects and mechanisms of hawthorn fruit polysaccharides (HP) in addressing non-alcoholic fatty liver disease (NAFLD).

PURPOSE

This study aims to investigate the effects of HP on NAFLD both in vivo and in vitro, and to elucidate the underlying mechanisms by which HP exerts its anti-NAFLD activity.

METHODS

NAFLD mice induced by a high-fat diet were employed as the in vivo model, while oleate/palmitate-induced HepG2 cells served as the in vitro model. H&E and Oil Red O staining were employed to examine fat accumulation in hepatocytes. Serum aminotransferase (ALT), aspartate aminotransferase (AST), hepatic malondialdehyde (MDA), superoxide dismutase (SOD), interleukin-1 beta (IL-1β), and interleukin-6 (IL-6) were measured using corresponding ELISA kits. Hepatic metabolomics analysis based on UHPLC-QTOF/MS was utilized to examine the role of HP in improving hepatic metabolic disorders. 16S rRNA sequencing was conducted to explore the effect of HP in alleviating gut microbiota dysbiosis. GC-MS was applied to detect short-chain fatty acids (SCFAs) to clarify the impact of HP in NAFLD mice.

RESULTS

HP significantly inhibited weight gain and hepatic fat accumulation in NAFLD mice. The reduction in serum ALT and AST levels indicated that HP mitigated liver function damage, while the decreased MDA levels and increased SOD activity suggested that HP alleviated hepatic oxidative stress. Furthermore, HP diminished the release of inflammatory cytokines such as IL-1β and IL-6 in the liver. HP significantly regulated metabolic pathways related to amino acids, lipids, and vitamins. Key metabolites such as l-tyrosine, urocanic acid, undecanedioic acid, oleamide, vitamin A, and vitamin B7 were restored to near-normal levels under the regulatory effects of HP. Gut microbiota dysbiosis in NAFLD mice was also ameliorated by HP, with genera such as unclassified_f__Lachnospiraceae and Dubosiella being notably affected. Correlation analysis indicated a significant correlation between the regulatory effects of HP on liver metabolism and gut microbiota. Additionally, HP showed no effect in vitro but increased acetic acid level in the gut of NAFLD mice.

CONCLUSIONS

These findings demonstrate that HP exhibits its anti-NAFLD effects, including alleviating lipid accumulation, liver dysfunction, oxidative stress, and inflammation. Mechanistically, HP primarily improves gut microbiota dysbiosis, thereby elevating intestinal SCFA levels and restoring hepatic metabolic disorders in NAFLD mice.

Probable targets and mechanism of ginsenoside Rg1 for non-alcoholic fatty liver disease: a study integrating network pharmacology, molecular docking, and molecular dynamics simulation

Ginsenoside Rg1 (GRg1), a key bioactive component of medicinal herbs, has shown beneficial effects on non-alcoholic fatty liver disease (NAFLD) and numerous other conditions. Nevertheless, the specific targets that are actively involved and the potential mechanisms underlying NAFLD treatment remain unclear. This study aimed to elucidate the therapeutic effects and mechanism of GRg1 in alleviating NAFLD using a combined approach of network pharmacology and molecular biology validation. The analysis yielded 294 targets for GRg1 and 1293 associated with NAFLD, resulting in 89 overlapping targets. Through protein-protein interactions (PPI) network topology analysis, 10 key targets were identified. Upon evaluating the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway and Gene Ontology (GO) analysis, GRg1 may exert therapeutic effects on NAFLD by negatively regulating the apoptotic process, insulin and endocrine resistance, the AGE-RAGE signaling pathway in diabetic complications, and the Estrogen, PI3K/Akt, and MAPK pathways. The three differential gene targets for Akt1, EGFR, and IGF1 were identified through the compound-target network in conjunction with the aforementioned methods. The molecular docking and molecular dynamics (MD) simulations showed that AKT1 and EGFR had a strong binding affinity with GRg1. Overall, our findings point to a novel therapeutic strategy involving NAFLD, with further in vivo and in vitro studies promising to deepen our comprehension and validate its potential advantages.Communicated by Ramaswamy H. Sarma.

Polyphenols synergistic drugs to ameliorate non-alcoholic fatty liver disease via signal pathway and gut microbiota: A review

BACKGROUND

Non-alcoholic fatty liver disease (NAFLD) is a common chronic liver disease with an increasing incidence worldwide. Single drug therapy may have toxic side effects and disrupt gut microbiota balance. Polyphenols are widely used in disease intervention due to their distinctive nutritional properties and medicinal value, which a potential gut microbiota modulator. However, there is a lack of comprehensive review to explore the efficacy and mechanism of combined therapy with drugs and polyphenols for NAFLD.

AIM OF REVIEW

Based on this, this review firstly discusses the link between NAFLD and gut microbiota, and outlines the effects of polyphenols and drugs on gut microbiota. Secondly, it examined recent advances in the treatment and intervention of NAFLD with drugs and polyphenols and the therapeutic effect of the combination of the two. Finally, we highlight the underlying mechanisms of polyphenol combined drug therapy in NAFLD. This is mainly in terms of signaling pathways (NF-κB, AMPK, Nrf2, JAK/STAT, PPAR, SREBP-1c, PI3K/Akt and TLR) and gut microbiota. Furthermore, some emerging mechanisms such as microRNA potential biomarker therapies may provide therapeutic avenues for NAFLD.

KEY SCIENTIFIC CONCEPTS OF REVIEW

Drawing inspiration from combination drug strategies, the use of active substances in combination with drugs for NAFLD intervention holds transformative and prospective potential, both improve NAFLD and restore gut microbiota balance while reducing the required drug dosage. This review systematically discusses the bidirectional interactions between gut microbiota and NAFLD, and summarizes the potential mechanisms of polyphenol synergistic drugs in the treatment of NAFLD by modulating signaling pathways and gut microbiota. Future researches should develop multi-omics technology to identify patients who benefit from polyphenols combination drugs and devising individualized treatment plans to enhance its therapeutic effect.

Comparative assessment of phenotypic markers in patients with chronic inflammation: Differences on Bifidobacterium concerning liver status

BACKGROUND

The relationship between systemic lupus erythematosus (SLE) and low-grade metabolic inflammation (MI) with the microbiota is crucial for understanding the pathogenesis of these diseases and developing effective therapeutic interventions. In this context, it has been observed that the gut microbiota plays a key role in the immune regulation and inflammation contributing to the exacerbation through inflammatory mediators. This research aimed to describe similarities/differences in anthropometric, biochemical, inflammatory, and hepatic markers as well as to examine the putative role of gut microbiota concerning two inflammatory conditions: SLE and MI.

METHODS

Data were obtained from a cohort comprising adults with SLE and MI. Faecal samples were determined by 16S technique. Statistical analyses compared anthropometric and clinical variables, and LEfSe and MetagenomeSeq were used for metagenomic data. An interaction analysis was fitted to investigate associations of microbiota with fatty liver index (FLI) depending on the inflammatory condition.

RESULTS

Participants with low-grade MI showed worse values in anthropometry and biochemicals compared with patients with SLE. The liver profile of patients with MI was unhealthier, while no relevant differences were found in most of the inflammatory markers between groups. LEfSe analysis revealed an overrepresentation of Bifidobacteriaceae family in SLE group. An interactive association between gut Bifidobacterium abundance and type of disease was identified for FLI values, suggesting an effect modification of the gut microbiota concerning liver markers depending on the inflammatory condition.

CONCLUSION

This study found phenotypical and microbial similarities and disparities between these two inflammatory conditions, evidenced in clinical and hepatic markers, and showed the interactive interplay between gut Bifidobacterium and liver health (measured by FLI) that occur in a different manner depending on the type of inflammatory disease. These results underscore the importance of personalized approaches and individual microbiota in the screening of different inflammatory situations, considering unique hepatic and microbiota profiles.

Navigating liver health with metabolomics: A comprehensive review

Non-alcoholic fatty liver disease (NAFLD) is the main cause of chronic liver disease worldwide, affecting one-fourth of the world's population. With more than half of the world's population, the Asia-Pacific region contributed 62.6 % of liver-related fatal incidents in 2015. Currently, liver imaging techniques such as computed tomography (CT), nuclear magnetic resonance (NMR) spectroscopy, and ultrasound are non-invasive imaging methods to diagnose the disease. A liver biopsy is the gold standard test for establishing the definite diagnosis of non-alcoholic steatohepatitis (NASH). However, there are still significant problems with sample variability and the procedure's invasiveness. Numerous studies have indicated various non-invasive biomarkers for both fibrosis and steatosis to counter the invasiveness of diagnostic procedures. Metabolomics could be a promising method for detecting early liver diseases, investigating pathophysiology, and developing drugs. Metabolomics, when utilized with other omics technologies, can result in a deeper understanding of biological systems. Metabolomics has emerged as a prominent research topic, offering extensive opportunities to investigate biomarkers for liver diseases that are both sensitive and specific. In this review, we have described the recent studies involving the use of a metabolomics approach in the diagnosis of liver diseases, which would be beneficial for the early detection and treatment of liver diseases.

Research hotspots and trends in gut microbiota and nonalcoholic fatty liver disease: A bibliometric study

BACKGROUND

Recent research indicates that the intestinal microbial community, known as the gut microbiota, may play a crucial role in the pathogenesis of nonalcoholic fatty liver disease (NAFLD). To understand this relationship, this study used a comprehensive bibliometric analysis to explore and analyze the currently little-known connection between gut microbiota and NAFLD, as well as new findings and possible future pathways in this field.

AIM

To provide an in-depth analysis of the current focus issues and research developments on the interaction between gut microbiota and NAFLD.

METHODS

In this study, all data were collected from the Web of Science Core Collection, and the related searches were completed on one day (February 21, 2024). The data were stored in plain text format to facilitate subsequent analysis. VOSviewer 1.6.20 and CiteSpace 6.1R6 Basic were used for knowledge graph construction and bibliometric analysis.

RESULTS

The study included a total of 1256 articles published from 2013 to 2023, and the number of published papers demonstrated an upward trend, reaching a peak in the last two years. The University of California, San Diego held the highest citation count, while Shanghai University of Traditional Chinese Medicine in China led in the number of published works. The journal "Nutrients" had the highest publication count, while "Hepatology" was the most frequently cited. South Korean author Suk Ki Tae was the most prolific researcher. The co-cited keyword cluster labels revealed ten major clusters, namely cortisol, endothelial dysfunction, carbohydrate metabolism, myocardial infarction, non-alcoholic steatohepatitis, lipotoxicity, glucagon-like peptide-1, non-islet dependent, ethnicity, and microRNA. Keyword outbreak analysis highlighted metabolic syndrome, hepatic steatosis, insulin resistance, hepatocellular carcinoma, cardiovascular disease, intestinal permeability, and intestinal bacterial overgrowth as prominent areas of intense research.

CONCLUSION

Through the quantitative analysis of relevant literature, the current research focus and direction of gut microbiota and NAFLD can be more clearly understood, which helps us better understand the pathogenesis of NAFLD, and also opens up innovative solutions and strategies for the treatment of NAFLD.

Microbiome and metabolomics reveal the effect of gut microbiota on liver regeneration of fatty liver disease

BACKGROUND

Metabolic dysfunction-associated fatty liver disease (MAFLD) is associated with impaired regenerative capacity and poor postoperative prognosis following hepatectomy. Previous research has highlighted the importance of the gut-liver axis in the physiological and pathological processes of the liver. However, the contribution of gut bacteria to the regeneration of livers with MAFLD and its metabolic regulatory mechanisms remain elusive.

METHODS

Partial hepatectomy (PHx) was performed on C57Bl/6J mice fed with high-fat diet (HFD) for 12 weeks. Pathological examination, immunohistochemistry, and qRT-PCR analysis were performed to assess the severity of steatosis and proliferative potential. The gut microbiome was examined by 16S rRNA gene sequencing and shotgun metagenomics, whereas liver metabolomics was analysed via untargeted and targeted metabolomics using liquid chromatography-tandem mass spectrometry (LC-MS).

FINDINGS

HFD-induced hepatic steatosis in mice led to impaired liver regeneration following PHx. The gut microbiota and liver metabolites were altered along with the liver regeneration process. Longitudinal time-series analysis revealed dynamic alterations in these data, whereas correlation analysis screened out bacterial candidates that potentially influence liver regeneration in MAFLD by modulating metabolic pathways. Among these bacteria, the dominant bacterium Akkermansia was selected for subsequent investigation. MAFLD mice gavaged with Akkermansia muciniphila (A. muciniphila) exhibited reduced liver lipid accumulation and accelerated liver regeneration, possibly through the regulation of the tricarboxylic acid (TCA) cycle.

INTERPRETATION

These data demonstrated the interplay between the gut microbiome, liver metabolomics, and liver regeneration in mice with MAFLD. A. muciniphila has the potential to serve as a clinical intervention agent to accelerate postoperative recovery in MAFLD.

FUNDING

This work was supported by the Research Project of Jinan Microecological Biomedicine Shandong Laboratory [JNL-2022008B]; the Zhejiang Provincial Natural Science Foundation of China [LZ21H180001]; the Fundamental Research Funds for the Central Universities [No. 2022ZFJH003].

Gut‑liver axis in liver disease: From basic science to clinical treatment (Review)

Incidence of a number of liver diseases has increased. Gut microbiota serves a role in the pathogenesis of hepatitis, cirrhosis and liver cancer. Gut microbiota is considered 'a new virtual metabolic organ'. The interaction between the gut microbiota and liver is termed the gut‑liver axis. The gut‑liver axis provides a novel research direction for mechanism of liver disease development. The present review discusses the role of the gut‑liver axis and how this can be targeted by novel treatments for common liver diseases.

Retinopathy in Metabolic Dysfunction-Associated Steatotic Liver Disease

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a multisystemic disease, i.e., influencing various organ systems beyond the liver and, thus, contributing to comorbidities. Characterized by excessive fat accumulation in the hepatocytes, MASLD is frequently linked to metabolic syndrome components, such as obesity, insulin resistance, dyslipidemia, and hypertension. Therefore, exploring the intricate connection between MASLD and other organ systems, including the eyes, seems to be essential. In this context, retinopathy has been investigated for its potential association with MASLD, since both conditions share common pathogenetic pathways. Chronic low-grade inflammation, oxidative stress, insulin resistance, and endothelial dysfunction are only some of those mechanisms contributing to disease progression and, possibly, determining the bidirectional interplay between the liver and retinal pathology. This narrative review aims to summarize data concerning the multisystemicity of MASLD, primarily focusing on its potential association with the eyes and, particularly, retinopathy. Identifying this possible association may emphasize the need for early screening and integrated management approaches that address the liver and eyes as interconnected components within the framework of a systemic disease. Further research is necessary to delineate the precise mechanisms and develop targeted interventions to mitigate the bidirectional impact between the liver and eyes, aiming to reduce the overall burden of disease and improve patient outcomes.

Association between the lymphocyte-to-high-density lipoprotein ratio and metabolic dysfunction-associated steatotic liver disease among US adults: a cross-sectional study from NHANES 2017 to 2020

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is a liver disease that is strongly associated with chronic low-grade inflammation. Stage 3 of MASLD is characterized by excessive formation of connective tissues, commonly referred to as liver fibrosis. Although numerous inflammatory markers have been identified and extensively studied, including the tumor necrosis factor-α and interleukin-6 have been studied [Byrne CD, Targher G. NAFLD: a multisystem disease. J Hepatol. 2015;62(1 Suppl):S47-64], the lymphocyte-to-high-density lipoprotein ratio (LHR) as a new biomarker that has not been sufficiently studied. This study aims to investigate the relationship between LHR levels and MASLD, determine its potential as a predictive marker for steatosis and fibrosis stages.

METHODS

This was a population-based study using data from 15,560 participants in the 2017-2020 National Health and Nutrition Examination Survey (NHANES) database. The study aimed to explore the relationship between LHR and MASLD. The disease progression was tracked by continuously measuring CAP and liver stiffness measurements. Participants who exhibited a median Controlled Attenuation Parameter (CAP) of 248 dB/m or higher were deemed to have hepatic steatosis. The LHR was calculated by dividing the lymphocyte count by the high-density lipoprotein cholesterol (HDL-C) level. Multivariate linear regression models were employed to explore the linear association between LHR and MASLD. Fitted smoothing curves and threshold effect analysis were employed to display nonlinear relationships. A two-part linear regression model was employed to estimate threshold effects. Subgroup analyses were conducted to determine the consistency of this association across various demographic groups.

RESULTS

A total of 6,950 adults aged 18 years and older were enrolled in the study, with an average age of 48.15 ± 17.10 years (49.14% male, 50.86% female). The adjusted multiple logistic regression analysis revealed a significant positive correlation between LHR and MASLD (OR: 1.64, 95% CI: 1.40-1.92). Using the complex two-piece linear regression model, we observed an inverted L-shaped association between LHR and CAP, suggesting a critical inflection point at -2.58. Subgroup analyses indicated a pronounced association of the LHR index with obese individuals (OR: 1.96, 95% CI: 1.66-2.32) and females (OR: 1.76, 95% CI: 1.25-2.46). There was no significant association between LHR and clinically significant fibrosis.

CONCLUSION

The LHR index is positively correlated with MASLD among US adults. Therefore, LHR may be a robust marker for early screening, diagnosis, and monitoring of treatment efficacy in clinical practice.

Clinical Significance of Serum Bile Acid Profiles in Fatty Liver

Objective

This study aims to investigate the alterations in serum bile acid profiles among individuals with fatty liver (including non-alcoholic fatty liver (NAFL) and alcoholic fatty liver (AFL) and evaluate their clinical significance when combined with liver enzyme levels.

Methods

A cohort of 110 individuals with fatty liver (including non-alcoholic fatty liver 58 individuals and alcoholic fatty liver 52 individuals) was selected from the Department of Gastroenterology at Wenzhou People's Hospital between January 2021 and December 2022, while a control group of 66 healthy individuals was recruited from the hospital's health examination center during the same period. Clinical data and blood samples were collected from all participants. Serum bile acid profiles were quantified using ultra-performance liquid chromatography coupled with tandem mass spectrometry (UPLC-MS/MS). Statistical analysis was conducted in conjunction with liver enzyme indicators.

Results

In the NAFL group, GCA, TCA, and TCDCA levels were significantly elevated compared to the control group, with GCA (AUC 0.754, sensitivity 0.707, specificity 0.712), TCA (AUC 0.770, sensitivity 0.724, specificity 0.712), and TCDCA (AUC 0.782, sensitivity 0.810, specificity 0.652) showing strong diagnostic value. In the AFL group, TCDCA, TCA, GCA, TUDCA, and GUDCA were significantly elevated, with AUC values ranging from 0.848 to 0.912. Among these, TUDCA had the highest sensitivity (0.885) and specificity (0.773) for AFL diagnosis. TUDCA (sensitivity 0.615, specificity 0.897) was the key bile acid distinguishing AFL from NAFL, with an optimal cut-off of 36.33 nmol/L. These bile acids show significant diagnostic potential for differentiating NAFL and AFL.

Conclusion

The bile acid profiles in both NAFL and AFL patients show changes, which hold potential clinical significance and may serve as serum biomarkers to differentiate NAFL from AFL.

Effect of Dendrobium nobile powder combined with conventional therapy on mild to moderate fatty liver

BACKGROUND

Nonalcoholic fatty liver disease (NAFLD) encompasses a variety of liver conditions impacting individuals who consume minimal or no alcohol. Recently, traditional Chinese medicine has been gradually used to treat mild to moderate fatty liver, among which Dendrobium nobile Lindl. powder has been affirmed by many doctors and patients to be effective. However, there is limited research on combining this treatment with standard therapies for mild to moderate NAFLD.

AIM

To survey the effect of combining Dendrobium nobile Lindl. powder with standard treatment on liver function and lipid metabolism disorder in patients with mild to moderate NAFLD.

METHODS

Eighty patients with mild to moderate NAFLD participated in this retrospective study, classified into two groups: The observation group (n = 40) and the control group (n = 40). In November 2020 and November 2022, the study was conducted at People's Hospital of Chongqing Liang Jiang New Area. The control group received standard treatment, while the observation group received Dendrobium nobile Lindl. powder based on the control group. The study compared differences in traditional Chinese medicine clinical syndrome scores, liver fibrosis treatment, liver function indicators, lipid levels, and serum inflammatory factor levels before and after treatment, and we calculated the incidence of adverse reactions for both groups.

RESULTS

The total effective rate was 97.50% in the observation group and 72.5% in the control group. After 8 weeks of treatment, the main and secondary symptom scores remarkably decreased, especially in the observation group (P < 0.05), and there was a significant reduction in the serum levels of hyaluronic acid (HA), laminin (LN), human rocollagen III (PC III), and collagen type IV (CIV). The levels of HA, LN, PC III, and CIV were significantly lower in the observation group (P < 0.05). After 8 weeks, both groups indicated remarkable improvements in liver function and blood lipid levels, with the observation group having even lower levels (P < 0.05). Serum levels of interleukin-1β, tumor necrosis factor-α, and interleukin-8 also dropped significantly. The observation group had a lower rate of adverse reactions (5.00%) compared to the control group (22.50%).

CONCLUSION

Adding Dendrobium nobile Lindl. powder to standard treatment has been found to remarkably improve symptoms and reduce inflammation in patients with mild to moderate fatty liver disease. It also enhances hepatic function and lipid profile, ameliorates liver fibrosis indices, and lowers the risk of side effects. Consequently, this therapeutic protocol shows promise for clinical implementation and dissemination.

Prebiotics targeting gut-liver axis to treat non-alcoholic fatty liver disease

Non-alcoholic steatohepatitis (NASH) is a high-prevalence, rapidly growing form of non-alcoholic fatty liver disease (NAFLD), which is closely linked to obesity and metabolic disorders. Gut microbiota has been increasingly recognized as a key factor in the onset of NAFLD in recent years. The liver can be strongly influenced by changes in the gut microbiota through the portal vein, giving the gut-liver axis a very important role in understanding the pathophysiology of liver diseases. A healthy intestinal barrier is characterized by selective permeability to nutrients, metabolites, water and bacterial products and its impairment may be a predisposing or aggravating condition for the progression of NAFLD. In most cases, NAFLD patients follow a Western diet pattern, which is closely linked to obesity and associated metabolic diseases, promoting inflammation, structural and behavioral changes in the gut microbiota. In fact, factors such as age, gender, genetic or environmental factors may induce a dysbiotic microbiota that promotes epithelial barrier dysfunction and increased intestinal permeability, favoring the progression of NAFLD. In this context, new dietary approaches, such as prebiotics, are emerging to prevent disease and maintain health. In this review, we reported the role of the gut-liver axis in the pathogenesis of NAFLD and investigated the potential therapeutic effect of prebiotics on the enhancement of intestinal barrier dysfunction, hepatic steatosis and, consequently, the progression of NAFLD.

Partially hydrolyzed guar gum suppresses binge alcohol-induced liver fat accumulation via gut environment modulation in mice

Alcohol-associated liver disease (ALD), including alcoholic fatty liver, is a serious problem in many countries, and its economic costs to society are enormous. There is evidence indicating the relations between gut environments and liver disease, and thus, improvement of gut environment is expected to be an effective approach for ALD prevention. In this study, we explored the preventive effect of partially hydrolyzed guar gum (PHGG) on ALD focusing on the gut-liver axis. Two weeks of PHGG pre-feeding suppressed the liver fat accumulation in the experimental binge alcohol model mouse. In cecal microbiome, PHGG pre-feeding increased beneficial Bifidobacterium with its metabolite acetate concentration and suppressed the alcohol-induced increase in the potential pathobiont Streptococcus. PHGG pre-feeding increased colonic gene expression of angiogenin genes, which act as antimicrobial peptides and decreased expression of genes for mast cell protease, which suggests a potential involvement in leaky gut. Correlation network analysis based on evaluated parameters revealed four relations worth noticing. (i) The abundance of Bifidobacterium positively correlated with cecal acetate. (ii) Cecal acetate negatively correlated with Streptococcus via colonic angiogenin expression. (iii) Streptococcus positively correlated with liver fat area. (iv) Cecal acetate had direct negative correlation with liver fat area. Considering these relations comprehensively, acetate produced by Bifidobacterium may be a key mediator in ALD prevention; it inhibited growth of potential pathobiont Streptococcus and also directly regulated liver lipid metabolism reaching through portal vein. This study demonstrated that regularly intake of PHGG may be effective in reducing the risk of alcoholic fatty liver via gut-liver axis.

Fecal microbiota transplantation validates the importance of gut microbiota in an ApoE-/- mouse model of chronic apical periodontitis-induced atherosclerosis

BACKGROUND

Chronic apical periodontitis (CAP) has been linked to the development of atherosclerosis, although the underlying mechanisms remain unclear. This study aimed to investigate the role of gut microbiota disruption in CAP-induced atherosclerosis development, focusing on trimethylamine N-oxide (TMAO)-related metabolites.

METHODS

The study utilized fecal microbiota transplantation (FMT) to transfer gut microbiota from mice with CAP to healthy mice. Atherosclerosis development was assessed by analyzing lesions in the aortic arch and aortic root. Serum lipid and inflammatory factor levels were measured. Composition and diversity of gut microbiota were analyzed using targeted metabolomics, with a focus on the ratio of Firmicutes to Bacteroidetes. The expression of hepatic flavin-containing monooxygenase 3 (FMO3) and serum TMAO levels were also evaluated.

RESULTS

Mice receiving gut microbiota from CAP mice showed increased atherosclerotic lesions compared to controls, without significant differences in serum lipid or inflammatory factor levels. Alterations in gut microbiota composition were observed, characterized by an increase in the Firmicutes to Bacteroidetes ratio. Peptostreptococcaceae abundance positively correlated with atherosclerosis severity, while Odoribacteraceae showed a negative correlation. No significant differences were found in hepatic FMO3 expression or serum TMAO levels.

CONCLUSIONS

The study confirms the role of gut microbiota disruption in CAP-mediated atherosclerosis development, independent of serum lipid or TMAO levels. Alterations in gut microbiota composition, particularly increased Firmicutes to Bacteroidetes ratio and specific bacterial families, were associated with atherosclerosis severity. These findings highlight the intricate interplay between gut microbiota and cardiovascular health in the context of CAP.

Helicobacter pylori Infection Is Not Associated with Nonalcoholic Fatty Liver Disease: A Two-Year Cohort Study

INTRODUCTION

Previous studies reported inconsistent results of the association between Helicobacter pylori infection and nonalcoholic fatty liver disease (NAFLD).

METHODS

A cohort study of 2,063 adults without NAFLD at baseline, who participated in a repeated health checkup including a 13C-urea breath test and abdominal ultrasonography, was conducted to evaluate the link between H. pylori infection and NAFLD development.

RESULTS

During a mean follow-up period of 1.7 years, we did not find a significant association between H. pylori infection and NAFLD (hazard ratio = 1.10 (0.86, 1.40), p = 0.4689). We also found that higher age, body mass index (BMI), systolic blood pressure (systolic BP), diastolic blood pressure (diastolic BP), fasting blood glucose, triglycerides, total cholesterol, low-density lipoprotein cholesterol (LDL-C), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) were risk factors, and high-density lipoprotein cholesterol (HDL-C) was a protective factor for NAFLD development.

CONCLUSION

H. pylori infection might not be positively related to NAFLD development.

Gut Microbiota and Liver Regeneration: A Synthesis of Evidence on Structural Changes and Physiological Mechanisms

Liver regeneration (LR) is a unique biological process with the ability to restore up to 70% of the organ. This allows for the preservation of liver resections for various liver tumors and for living donor liver transplantation (LDLT). However, in some cases, LR is insufficient and interventions that can improve LR are urgently needed. Gut microbiota (GM) is one of the factors influencing LR, as the liver and intestine are intimately connected through the gut-liver axis. Thus, healthy GM facilitates normal LR, whereas dysbiosis leads to impaired LR due to imbalance of bile acids, inflammatory cytokines, microbial metabolites, signaling pathways, etc. Therefore, GM can be considered as a new possible therapeutic target to improve LR. In this review, we critically observe the current knowledge about the influence of gut microbiota (GM) on liver regeneration (LR) and the possibility to improve this process, which may reduce complication and mortality rates after liver surgery. Although much research has been done on this topic, more clinical trials and systemic reviews are urgently needed to move this type of intervention from the experimental phase to the clinical field.

The potential influence of microplastics on the microbiome and disease susceptibility in sea turtles

Microplastics (MPs) are particles with sizes of ≤5 mm formed when plastic materials break down. These contaminants are often found in marine environments, making it easy for sea turtles to ingest them and for their microbiome to be exposed. MPs can disrupt microbiome balance, leading to dysbiosis and making organisms more susceptible to diseases. Owing to the significance of these processes, it is crucial to dedicate research to studying the metabolic and genetic analysis of the gut microbiome in sea turtles. The objective of this study was to describe the effects of exposure to MPs on the gut microbiome of sea turtles, based on current knowledge. This review also aimed to explore the potential link between MP exposure and disease susceptibility in these animals. We show that the metabolites produced by the gut microbiome, such as short-chain fatty acids (SCFAs), polyamines, and polysaccharide A, can regulate the expression of host genes. Regulation occurs through various mechanisms, including histone acetylation, DNA methylation, and the modulation of cytokine gene expression. These processes are essential for preserving the integrity of the gut mucosa and enhancing the functionality of immune cells. Exposure to MPs disrupts the gut microbiome and alters gene expression, leading to immune system disturbances in sea turtles. This vulnerability makes turtles more susceptible to opportunistic microorganisms such as chelonid alphaherpesvirus 5 (ChAHV5), which is linked to the development of fibropapillomatosis (FP). Additionally, targeted dietary interventions or the use of live microorganisms such as probiotics can help restore microbial biodiversity and recover lost metabolic pathways. The goal of these interventions is to restore the functionality of the immune system in sea turtles undergoing rehabilitation at specialized centers. The gut microbiome plays a crucial role in sea turtle health, sparking discussions and investigations that can potentially lead to promising treatments for these animals.

Gut microbiota-NLRP3 inflammasome crosstalk in metabolic dysfunction-associated steatotic liver disease

Nonalcoholic fatty liver disease (NAFLD) is a chronic liver disease associated with metabolic dysfunction, ranging from hepatic steatosis with or without mild inflammation to nonalcoholic steatohepatitis, which can rapidly progress to liver fibrosis and even liver cancer. In 2023, after several rounds of Delphi surveys, a new consensus recommended renaming NAFLD as metabolic dysfunction-associated steatotic liver disease (MASLD). Ninety-nine percent of NAFLD patients meet the new MASLD criteria related to metabolic cardiovascular risk factors under the "multiple parallel hits" of lipotoxicity, insulin resistance (IR), a proinflammatory diet, and an intestinal microbiota disorder, and previous research on NAFLD remains valid. The NLRP3 inflammasome, a well-known member of the pattern recognition receptor (PRR) family, can be activated by danger signals transmitted by pathogen-associated molecular patterns (PAMPs) and damage-associated molecular patterns (DAMPs), as well as cytokines involved in immune and inflammatory responses. The activation of the NLRP3 inflammasome pathway by MASLD triggers the production of the inflammatory cytokines IL-1β and IL-18. In MASLD, while changes in the composition and metabolites of the intestinal microbiota occur, the disrupted intestinal microbiota can also generate the inflammatory cytokines IL-1β and IL-18 by damaging the intestinal barrier, negatively regulating the liver on the gut-liver axis, and further aggravating MASLD. Therefore, modulating the gut-microbiota-liver axis through the NLRP3 inflammasome may emerge as a novel therapeutic approach for MASLD patients. In this article, we review the evidence regarding the functions of the NLRP3 inflammasome and the intestinal microbiota in MASLD, as well as their interactions in this disease.

Development of Liver Fibrosis Represented by the Fibrosis-4 Index Is a Specific Risk Factor for Tubular Injury in Individuals with Type 2 Diabetes

Although hyperglycemia and hypertension are well-known risk factors for glomerular injury in individuals with type 2 diabetes (T2D), specific risk factors for tubular injury remain unclear. We aimed to clarify the differences between risk factors for glomerular injury and risk factors for tubular injury in individuals with T2D. We categorized 1243 subjects into four groups based on urinary biomarkers, including the albumin-to-creatinine ratio (uACR) and L-type fatty acid-binding protein-to-creatinine ratio (uL-ABPCR) as a normal (N) group (uACR < 30 mg/gCr and uL-FABPCR < 5 μg/gCr; n = 637), a glomerular specific injury (G) group (uACR ≥ 30 mg/gCr and uL-FABPCR < 5 μg/gCr; n = 248), a tubular specific injury (T) group (uACR < 30 mg/gCr and uL-FABPCR ≥ 5 μg/gCr; n = 90), and a dual injury (D) group (uACR ≥ 30 mg/gCr and uL-FABPCR ≥ 5 μg/gCr; n = 268). Logistic regression analysis referencing the N group revealed that BMI, current smoking, and hypertension were risk factors for the G group, creatinine (Cr) and Fibrosis-4 (FIB-4) index were risk factors for the T group, and BMI, hypertension, HbA1c, Cr, and duration of diabetes were risk factors for the D group. While hypertension was a distinct specific risk factor for glomerular injury, the FIB-4 index was a specific contributor to the prevalence of tubular injury. On the other hand, the logistic regression analysis revealed that the hepatic steatosis index (HSI) did not show any significant association with the G group, T group, or D group. Taken together, the development of liver fibrosis rather than liver steatosis is an inherent threat relating to tubular injury in individuals with T2D.

Multi-omics analysis of the biological mechanism of the pathogenesis of non-alcoholic fatty liver disease

Background

Non-alcoholic fatty liver disease (NAFLD) is a type of liver metabolic syndrome. Employing multi-omics analyses encompassing the microbiome, metabolome and transcriptome is crucial for comprehensively elucidating the biological processes underlying NAFLD.

Methods

Hepatic tissue, blood and fecal samples were obtained from 9 NAFLD model mice and 8 normal control mice. Total fecal microbiota DNA was extracted, and 16S rRNA was amplified, to analyze alterations in the gut microbiota (GM) induced by NAFLD. Subsequently, diagnostic strains for NAFLD were screened, and their functional aspects were examined. Differential metabolites and differentially expressed genes were also screened, followed by enrichment analysis. Correlations between the differential microbiota and metabolites, as well as between the DEGs and differential metabolites were studied. A collinear network involving key genes-, microbiota-and metabolites was constructed.

Results

Ileibacterium and Ruminococcaceae, both belonging to Firmicutes; Olsenella, Duncaniella and Paramuribaculum from Bacteroidota; and Bifidobacterium, Coriobacteriaceae_UCG_002 and Olsenella from Actinobacteriota were identified as characteristic strains associated with NAFLD. Additionally, differentially expressed metabolites were predominantly enriched in tryptophan, linoleic acid and methylhistidine metabolism pathways. The functions of 2,510 differentially expressed genes were found to be associated with disease occurrence. Furthermore, a network comprising 8 key strains, 14 key genes and 83 key metabolites was constructed.

Conclusion

Through this study, we conducted a comprehensive analysis of NAFLD alterations, exploring the gut microbiota, genes and metabolites of the results offer insights into the speculated biological mechanisms underlying NAFLD.

Probiotic Lactobacillus fermentum TSF331, Lactobacillus reuteri TSR332, and Lactobacillus plantarum TSP05 improved liver function and uric acid management-A pilot study

Metabolic-associated fatty liver disease (MAFLD) is predominantly associated with metabolic disturbances representing aberrant liver function and increased uric acid (UA) levels. Growing evidences have suggested a close relationship between metabolic disturbances and the gut microbiota. A placebo-controlled, double-blinded, randomized clinical trial was therefore conducted to explore the impacts of daily supplements with various combinations of the probiotics, Lactobacillus fermentum TSF331, Lactobacillus reuteri TSR332, and Lactobacillus plantarum TSP05 with a focus on liver function and serum UA levels. Test subjects with abnormal levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and UA were recruited and randomly allocated into six groups. Eighty-two participants successfully completed the 60-day intervention without any dropouts or occurrence of adverse events. The serum AST, ALT, and UA levels were significantly reduced in all treatment groups (P < 0.05). The fecal microbiota analysis revealed the intervention led to an increase in the population of commensal bacteria and a decrease in pathobiont bacteria, especially Bilophila wadsworthia. The in vitro study indicated the probiotic treatments reduced lipid accumulation and inflammatory factor expressions in HepG2 cells, and also promoted UA excretion in Caco-2 cells. The supplementation of multi-strain probiotics (TSF331, TSR332, and TSP05) together can improve liver function and UA management and may have good potential in treating asymptomatic MAFLD. Trial registration. The trial was registered in the US Library of Medicine (clinicaltrials.gov) with the number NCT06183801 on December 28, 2023.

Hepatocyte programmed cell death: the trigger for inflammation and fibrosis in metabolic dysfunction-associated steatohepatitis

By replacing and removing defective or infected cells, programmed cell death (PCD) contributes to homeostasis maintenance and body development, which is ubiquitously present in mammals and can occur at any time. Besides apoptosis, more novel modalities of PCD have been described recently, such as necroptosis, pyroptosis, ferroptosis, and autophagy-dependent cell death. PCD not only regulates multiple physiological processes, but also participates in the pathogenesis of diverse disorders, including metabolic dysfunction-associated steatotic liver disease (MASLD). MASLD is mainly classified into metabolic dysfunction-associated steatotic liver (MASL) and metabolic dysfunction-associated steatohepatitis (MASH), and the latter putatively progresses to cirrhosis and hepatocellular carcinoma. Owing to increased incidence and obscure etiology of MASH, its management still remains a tremendous challenge. Recently, hepatocyte PCD has been attracted much attention as a potent driver of the pathological progression from MASL to MASH, and some pharmacological agents have been proved to exert their salutary effects on MASH partly via the regulation of the activity of hepatocyte PCD. The current review recapitulates the pathogenesis of different modalities of PCD, clarifies the mechanisms underlying how metabolic disorders in MASLD induce hepatocyte PCD and how hepatocyte PCD contributes to inflammatory and fibrotic progression of MASH, discusses several signaling pathways in hepatocytes governing the execution of PCD, and summarizes some potential pharmacological agents for MASH treatment which exert their therapeutic effects partly via the regulation of hepatocyte PCD. These findings indicate that hepatocyte PCD putatively represents a new therapeutic point of intervention for MASH.

Global research trends on gut microbiota and metabolic dysfunction-associated steatohepatitis: Insights from bibliometric and scientometric analysis

Background

Metabolic dysfunction-associated steatohepatitis (MASH) is an inflammatory subtype of metabolic dysfunction-associated steatotic liver disease (MASLD) has recently been proposed as a replacement term for NAFLD, a common, multifactorial and poorly understood liver disease whose incidence is increasing worldwide. In recent years, there has been increasing scientific interest in exploring the relationship between gut microbiota and MASH. To learn more about the gut microbiota in MASH, this study aims to provide a comprehensive analysis of the knowledge structure and research hotspots from a bibliometric perspective.

Methods

We searched the Web of Science Core Collection for articles and reviews that covered the connections between gut microbiota and MASH over the last decade. The Online Analysis Platforms, VOSviewer, CiteSpace, the R tool "bibliometrix" were used to analyzed existing publications trends and hotspots.

Results

A total of 4,069 documents related to the interaction between gut microbiota and MASH were retrieved from 2014 to 2023. The number of annual publications increased significantly over the last decade, particularly in the United States and China. The University of California-San Diego was the most productive institution, while researcher Rohit Loomba published the most papers in the field. Younossi ZM was ranked as the first co-cited author and largest contributor of highly cited articles in the field. Gastroenterology and hepatology were the most common specialty category. The most cited journal in the last decade was Hepatology. The Keyword Bursts analysis highlighted the importance of studying the association between gut microbiota and MASH, as well as related factors such as metabolic syndrome, insulin resistance, endotoxemia and overgrowth of gut bacteria. Keyword clusters with co-citation were used to illustrate important topics including intestinal permeability, insulin sensitivity and liver immunology. The most common keywords include insulin resistance, obesity, dysbiosis, inflammation and oxidative stress, which are current hotspots.

Conclusion

Our analysis highlights key aspects of this field and emphasizes multiorgan crosstalk in MASLD/MASH pathogenesis. In particular, the central role of the gut-liver axis and the significant influence of gut microbiota dysbiosis on disease progression are highlighted. Furthermore, our results highlight the transformative potential of microbiota-specific therapies and cover the way for innovative healthcare and pharmaceutical strategies.

Long-term outcomes in lean and non-lean NAFLD patients: a systematic review and meta-analysis

BACKGROUND

Although nonalcoholic fatty liver disease (NAFLD) commonly occurs in overweight or obese individuals, it is increasingly being identified in the lean population. The association between lean and an increased risk of all-cause mortality among patients with NAFLD remains controversial. We aimed to perform a systematic review and meta-analysis of the literature to evaluate this association and compare the long-term outcomes of lean NAFLD patients and non-lean NAFLD patients.

METHODS

For this systematic review and meta-analysis, we searched PubMed, Embase, Cochrane Library, Web of Science, China National Knowledge Infrastructure (CNKI), Wan Fang, and Chinese Biomedical Literature Database (CBM) from inception to October 15, 2021, for relevant original research articles without any language restrictions. Our primary outcome was to compare the all-cause mortality in lean NAFLD patients and non-lean NAFLD patients by qualitative synthesis. Relative risks (RRs) and corresponding 95% confidential intervals (CIs) were pooled with a random effect model. Heterogeneity was evaluated using I-squared (I²) statistics while publication bias was determined using Egger's tests. Subgroup and sensitivity analyses were performed. As for secondary outcomes, we estimated total, cardiovascular, and liver-related mortality, as well as the incidence of diabetes, hypertension, cirrhosis, and cancer in lean and non-lean individuals with NAFLD by quantitative synthesis. Person-years of follow-up were used as the denominator to estimate the mortality and incidence.

RESULTS

We identified 12 studies (n = 26,329), 7 of which (n = 7924) were used to evaluate the risk of all-cause mortality between lean and non-lean NAFLD patients. Lean patients with NAFLD were found to be at an elevated risk of death compared to non-lean patients (RR = 1.39, 95% CI 1.08-1.82, heterogeneity: I² = 43%). Among the lean NAFLD population, all-cause mortality was 13.3 (95% CI: 6.7-26.1) per 1000 person-years, 3.6 (95% CI: 1.0-11.7) for liver-related mortality, and 7.7 (95% CI: 6.4-9.2) for cardiovascular-related mortality. The incidence of new-onset diabetes was 13.7 (95% CI 8·2-22.7) per 1000 person-years, new-onset hypertension was 56.1 (95% CI: 40.2-77.9), cirrhosis was 2.3 (95% CI: 1.0-5.0), and cancer was 25.7 (95% CI: 20.3-32.4).

CONCLUSIONS

Lean patients with NAFLD had a higher risk of all-cause death than non-lean patients. Body mass index (BMI) should not be used as a criterion to determine whether further observation and therapy of patients with NAFLD are warranted.

Role of Nonalcoholic Fatty Liver Disease in Periodontitis: A Bidirectional Relationship

Nonalcoholic fatty liver disease (NAFLD) and periodontitis share common risk factors such as obesity, insulin resistance (IR), and dyslipidemia, which contribute to systemic inflammation. It has been suggested that a bidirectional relationship exists between NAFLD and periodontitis, indicating that one condition may exacerbate the other. NAFLD is characterized by excessive fat deposition in the liver and is associated with low-grade chronic inflammation. There are several risk factors for the development of NAFLD, including gender, geriatric community, race, ethnicity, poor sleep quality and sleep deprivation, physical activity, nutritional status, dysbiosis gut microbiota, increased oxidative stress, overweight, obesity, higher body mass index (BMI), IR, type 2 diabetes mellitus (T2DM), metabolic syndrome (MetS), dyslipidemia (hypercholesterolemia), and sarcopenia (decreased skeletal muscle mass). This systemic inflammation can contribute to the progression of periodontitis by impairing immune responses and exacerbating the inflammatory processes in the periodontal tissues. Furthermore, individuals with NAFLD often exhibit altered lipid metabolism, which may affect oral microbiota composition, leading to dysbiosis and increased susceptibility to periodontal disease. Conversely, periodontitis has been linked to the progression of NAFLD through mechanisms involving systemic inflammation and oxidative stress. Chronic periodontal inflammation can release pro-inflammatory cytokines and bacterial toxins into the bloodstream, contributing to liver inflammation and exacerbating hepatic steatosis. Moreover, periodontitis-induced oxidative stress may promote hepatic lipid accumulation and IR, further aggravating NAFLD. The interplay between NAFLD and periodontitis underscores the importance of comprehensive management strategies targeting both conditions. Lifestyle modifications such as regular exercise, a healthy diet, and proper oral hygiene practices are crucial for preventing and managing these interconnected diseases. Additionally, interdisciplinary collaboration between hepatologists and periodontists is essential for optimizing patient care and improving outcomes in individuals with NAFLD and periodontitis.

Role of gut-liver axis and glucagon-like peptide-1 receptor agonists in the treatment of metabolic dysfunction-associated fatty liver disease

Metabolic dysfunction-associated fatty liver disease (MAFLD) is a hepatic manifestation of the metabolic syndrome. It is one of the most common liver diseases worldwide and shows increasing prevalence rates in most countries. MAFLD is a progressive disease with the most severe cases presenting as advanced fibrosis or cirrhosis with an increased risk of hepatocellular carcinoma. Gut microbiota play a significant role in the pathogenesis and progression of MAFLD by disrupting the gut-liver axis. The mechanisms involved in maintaining gut-liver axis homeostasis are complex. One critical aspect involves preserving an appropriate intestinal barrier permeability and levels of intestinal lumen metabolites to ensure gut-liver axis functionality. An increase in intestinal barrier permeability induces metabolic endotoxemia that leads to steatohepatitis. Moreover, alterations in the absorption of various metabolites can affect liver metabolism and induce liver steatosis and fibrosis. Glucagon-like peptide-1 receptor agonists (GLP-1 RAs) are a class of drugs developed for the treatment of type 2 diabetes mellitus. They are also commonly used to combat obesity and have been proven to be effective in reversing hepatic steatosis. The mechanisms reported to be involved in this effect include an improved regulation of glycemia, reduced lipid synthesis, β-oxidation of free fatty acids, and induction of autophagy in hepatic cells. Recently, multiple peptide receptor agonists have been introduced and are expected to increase the effectiveness of the treatment. A modulation of gut microbiota has also been observed with the use of these drugs that may contribute to the amelioration of MAFLD. This review presents the current understanding of the role of the gut-liver axis in the development of MAFLD and use of members of the GLP-1 RA family as pleiotropic agents in the treatment of MAFLD.

Lipidomic Analysis Reveals Alterations in Hepatic FA Profile Associated With MASLD Stage in Patients With Obesity

CONTEXT

Metabolic dysfunction-associated steatotic liver disease (MASLD) is characterized by the intracellular lipid accumulation in hepatocytes. Excess caloric intake and high-fat diets are considered to significantly contribute to MASLD development.

OBJECTIVE

To evaluate the hepatic and serum fatty acid (FA) composition in patients with different stages of MASLD, and their relationship with FA dietary intake and MASLD-related risk factors.

METHODS

This was a case-control study in patients with obesity undergoing bariatric surgery at a university hospital between January 2020 and December 2021. Participants were distributed in 3 groups: no MASLD (n = 26), steatotic liver disease (n = 33), and metabolic dysfunction-associated steatohepatitis (n = 32). Hepatic and serum FA levels were determined by gas chromatography-mass spectrometry. Nutritional status was evaluated using validated food frequency questionnaires. The hepatic expression of genes involved in FA metabolism was analyzed by reverse transcription quantitative polymerase chain reaction.

RESULTS

The hepatic, but not serum, FA profiles were significantly altered in patients with MASLD compared with those without MASLD. No differences were observed in FA intake between the groups. Levels of C16:0, C18:1, and the C18:1/C18:0 ratio were higher, while C18:0 levels and C18:0/C16:0 ratio were lower in patients with MASLD, being significantly different between the 3 groups. Hepatic FA levels and ratios correlated with histopathological diagnosis and other MASLD-related parameters. The expression of genes involved in the FA metabolism was upregulated in patients with MASLD.

CONCLUSION

Alterations in hepatic FA levels in MASLD patients were due to enhancement of de novo lipogenesis in the liver.

Cu exposure induces liver inflammation via regulating gut microbiota/LPS/liver TLR4 signaling axis

Copper (Cu) serves as an essential cofactor in all organisms, yet excessive Cu exposure is widely recognized for its role in inducing liver inflammation. However, the precise mechanism by which Cu triggers liver inflammation in ducks, particularly in relation to the interplay in gut microbiota regulation, has remained elusive. In this investigation, we sought to elucidate the impact of Cu exposure on liver inflammation through gut-liver axis in ducks. Our findings revealed that Cu exposure markedly elevated liver AST and ALT levels and induced liver inflammation through upregulating pro-inflammatory cytokines (IL-1β, IL-6 and TNF-α) and triggering the LPS/TLR4/NF-κB signaling pathway. Simultaneously, Cu exposure induced alterations in the composition of intestinal flora communities, notably increasing the relative abundance of Sphingobacterium, Campylobacter, Acinetobacter and reducing the relative abundance of Lactobacillus. Cu exposure significantly decreased the protein expression related to intestinal barrier (Occludin, Claudin-1 and ZO-1) and promoted the secretion of intestinal pro-inflammatory cytokines. Furthermore, correlation analysis was observed that intestinal microbiome and gut barrier induced by Cu were closely related to liver inflammation. Fecal microbiota transplantation (FMT) experiments further demonstrated the microbiota-depleted ducks transplanting fecal samples from Cu-exposed ducks disturbed the intestinal dysfunction, which lead to impaire liver function and activate the liver inflammation. Our study provided insights into the mechanism by which Cu exposure induced liver inflammation in ducks through the regulation of gut-liver axis. These results enhanced our comprehension of the potential mechanisms driving Cu-induced hepatotoxicity in avian species.

Gut-liver axis: Potential mechanisms of action of food-derived extracellular vesicles

Food-derived extracellular vesicles (FEVs) are nanoscale membrane vesicles obtained from dietary materials such as breast milk, plants and probiotics. Distinct from other EVs, FEVs can survive the harsh degrading conditions in the gastrointestinal tract and reach the intestines. This unique feature allows FEVs to be promising prebiotics in health and oral nanomedicine for gut disorders, such as inflammatory bowel disease. Interestingly, therapeutic effects of FEVs have recently also been observed in non-gastrointestinal diseases. However, the mechanisms remain unclear or even mysterious. It is speculated that orally administered FEVs could enter the bloodstream, reach remote organs, and thus exert therapeutic effects therein. However, emerging evidence suggests that the amount of FEVs reaching organs beyond the gastrointestinal tract is marginal and may be insufficient to account for the significant therapeutic effects achieved regarding diseases involving remote organs such as the liver. Thus, we herein propose that FEVs primarily act locally in the intestine by modulating intestinal microenvironments such as barrier integrity and microbiota, thereby eliciting therapeutic impact remotely on the liver in non-gastrointestinal diseases via the gut-liver axis. Likewise, drugs delivered to the gastrointestinal system through FEVs may act via the gut-liver axis. As the liver is the main metabolic hub, the intestinal microenvironment may be implicated in other metabolic diseases. In fact, many patients with non-alcoholic fatty liver disease, obesity, diabetes and cardiovascular disease suffer from a leaky gut and dysbiosis. In this review, we provide an overview of the recent progress in FEVs and discuss their biomedical applications as therapeutic agents and drug delivery systems, highlighting the pivotal role of the gut-liver axis in the mechanisms of action of FEVs for the treatment of gut disorders and metabolic diseases.

Semaglutide alters gut microbiota and improves NAFLD in db/db mice

Non-alcoholic fatty liver disease (NAFLD) is the most common liver disease associated with type 2 diabetes mellitus (T2D). NAFLD can progress to nonalcoholic steatohepatitis (NASH), cirrhosis, and even cancer, all of which have a very poor prognosis. Semaglutide, a novel glucagon-like peptide-1 (GLP-1) receptor agonist, has been recognized as a specific drug for the treatment of diabetes. In this study, we used a gene mutation mouse model (db/db mice) to investigate the potential liver-improving effects of semaglutide. The results showed that semaglutide improved lipid levels and glucose metabolism in db/db mice. HE staining and oil red staining showed alleviation of liver damage and reduction of hepatic lipid deposition after injection of semaglutide. In addition, semaglutide also improved the integrity of gut barrier and altered gut microbiota, especially Alloprevotella, Alistpes, Ligilactobacillus and Lactobacillus. In summary, our findings validate that semaglutide induces modifications in the composition of the gut microbiota and ameliorates NAFLD, positioning it as a promising therapeutic candidate for addressing hepatic steatosis and associated inflammation.